Durability testing of silvered-glass mirrors

Abstract

Durability analysis of solar mirrors is attracting attention from Concentrating Solar Power (CSP) developers because guaranties of a suitable optical behavior during the whole service life time are required. To give realistic life time estimations in affordable time, research institutes are investing a lot of effort in developing appropriate accelerated aging tests. In this paper, an extensive test campaign of accelerated aging tests has been performed with silvered-glass mirrors from several manufacturers. Three commercial outdoor-proven products, a not outdoor-proven mirror prototype and two mirrors which showed degradation after only three years of outdoor operation in Spain and Australia have been tested. The accelerated aging tests were conducted for an extended period of time in order to determine the testing time at which the two mirror materials that showed degradation outdoors start to fail under the accelerated conditions. The degradation of the outdoor exposed mirrors is analyzed microscopically and compared to the degradation appearing under accelerated aging. The presented data on accelerated testing represents useful information for standardization of durability testing of solar mirrors.